Instead clone the libbpf repo at a specific hash during setup.
This is to fix an issue whereby submodules are not included
in the tarball and therefore won't be updated/fetched during
setup after unzipping the tarball.
This is to potentinally reduce issues with folks
using different versions of libbpf at runtime.
This also:
- makes static linking of libbpf the default
- adds steps in `meson setup` to fetch libbpf and make it
This reverts commit 5b9b953e3c, reversing
changes made to a7b39f24e2.
The current git submodule approach is a bit cumbersome and doesn't provide a
unified build environment for both libbpf and scx scheds. Also, the build
instruction doesn't seem to work. Let's revert it for now.
